Microalgal diversity as an indicator of the state of the environment of water bodies of Doon valley in Western Himalaya, India

Abstract

The management of biodiversity is of utmost importance for environmental sustainability and conservation. Microalgal diversity/assemblage serves as the biological indicators of water bodies’ environment. In the present study, water samples were collected from ten rivers, three lakes and a stream within Doon valley of Western Himalayas, India. This is the first complete and holistic study of microalgal diversity of Doon valley. Different physico-chemical parameters of the water samples like pH, temperature, turbidity, odour and colour were studied. Microalgal diversity was evaluated to serve as bioindicators of the natural riverine and lacustrine habitats. In addition, ArcGIS software tool was applied to create prediction maps for depicting the physico-chemical characteristics of water samples and microalgal diversity. A geostatistical analysis was devised to make these prediction maps. Further, the microalgal diversity was confirmed using PAST tool through diversity indices. The study confirmed the microalgal biodiversity with Shannon (2.59–2.76) and Simpson’s (0.91–0.93) indices. The microalgal diversity has been also confirmed with the parametric data (pH, temperature, turbidity) and non-parametric data (colour, odour) of collected water samples. The study recorded a total of 33 taxa belonging to 27 genera of microalgae. The microalgal species found in the lentic and lotic habitats belonged to the Chlorophyta, Myxophyta, Bacillariophyta, Euglenophyta and Dinophyta divisions. Three microalgal species belonging to Chlorophyta division were newly reported for Doon valley. Multivariate cluster analysis, non-metric multidimensional scaling and canonical correspondence analysis were appropriately employed to correlate the microalgal diversity with sampling sites and environmental variables. Further, microalgal diversity data was collated and used as specific indicators for pollution status of the sampled sites. Algal Genus Pollution Index (bearing algal indicator genus) has been employed to assess the organic pollution status of the water bodies. The results indicated rivers Rispana and Bindal as the most organically polluted while River Nun as the least polluted among all the lentic and lotic water bodies of Doon valley.